Circuit-controlling device



P. F. SHIVERS.

CIRCUIT CONTROLLING DEVICE.

APPLICATION FILED FEB. 3. 1920.

1,357,734, Patented Nov. 2, 1920.

Inventor: pau F.5hivers,

H is Attor neg.

uNirso STATES PATENT OFFICE.

PAUL F. SHIVERS, OF FORT WAYNE, INDIANA, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

CIRCUIT-CONTROLLING DEVICE.

Specification of Letters Patent,

Patented Nov. 2, 1920.

Application filed February a, 1920. Serial No. 356,102.

controlling devices and more particularly to a centrifugally operated switch for control-' ling an electric circuit when a machine to which the switch is attached reaches a predetermined speed. An object of my invention is to provide a novel and simple con struction of a centrifugally operated switch whereby it can be easily and readily adjusted to operate at different speeds.

The construction and operation of my switch can be best understood from the following description taken in connection with the accompanying drawings in which Figures 1 and 2 show respectively an end view and aside view, partly in section, of one modification of my invention; Figs. 3 and 4 show respectively the end view and side view, partly in section, of another modification of my invention, and Fig. 5 a diagram of the connections of one embodiment of my invention.

Referring first to Figs. 1 and 2, 1 represents a portion of a shaft, the end of which is hollow. A tapered plug 2 is placed in the hollow portion of the shaft 1 and in order that the position of the plug may be readily changed in the shaft, the end of the plug is threaded. A hub 3 is fastened to the shaft in any suitable manner such as by means of screws, not shown. Upon this hub 3, collector rings 4 and 5 are mounted, these rings being insulated from each other and from the hub in any well-known manner. In the particular modification shown, the collector rings 4 and 5 are insulated from each other by a ring 6 .of insulating material and are insulated from the hub 3 by the insulation bushing 7 and the insulation rings.8 and 9. The slip rings 4 and 5 and the insulation rings 6, 8 and 9 and bushing 7 are,

firmly held together between a collar 11 of the hub anda washer 10, the washer being held in position by the rounded-over end of the hub 3.

A contact block 12 is fastened to the collector ring 4 by means of screws 13 which entend through the insulation ring 6, the slip ring 5 and an insulation plate 14 inserted between the slip ring 5 and the contact block 12. The screws 13 are insulated from the slip ring 5 by means of sleeves 15 of insulating material. The contact block carries a contact 16 which is electrically connected thereto and therefore is electrically connected to the slip ring 4 by the screws 13. The block 12 also supports an adjustable screw 17 which carries a stop 18 of insulating material.

The slip ring 5 is provided with a lug 19 to which is fastened, by means of screws, one end of a spring 20, the other end of which carries a contact 21 which is adapted to engage the contact 16 carried by the contact block 12. The contact 21 is normally held out of engagement with the contact 16 by a flat spring 22, one end of which presses against the spring 20 and holds it against the sto 18. The opposite end of the spring 22 is astened, by means of screws, to an adjustable lever 23 which is pivotally mounted on a stud 24, fastened to the slip ring 5. One end of the lever 23 engages the top of a pin 25 ofinsulating material which extends through a hole in the shaft and engages the tapered portion of the plug 2.

In order to prevent the lever 23 from being moved out of engagement with the top of pin 25 by centrifugal force, the portion of the lever on the opposite side of the stud 24 from the side engaging the pin 25 is made heavier and so arranged with respect to the shaft 1 that it has the larger turning moment, about the stud 24. With this arrangement, centrifugal force tends to hold the lever 23 in engagement with the top of pin 25, and therefore the position of the lever is not changed by the rotation of the shaft. In order to balance the switch on the shaft, the slip ring 5 is provided with a projection 26 on the opposite side of the shaft with respect to the lever 23 and the contact block 12.

It will be evident that with this arrangement of parts the pressure exerted by the spring 20 against spring 22 can be easily and readily adjustable by merely screwing the plug 2 in or out of the hollow portion of the shaft, thereby moving the pin 25 up or down, which in turn changes the position of the lever 23 and varies the pressure of the spring 22 against the spring 20. I

Referring now to Figs. 3 and 4, another modification of my invention is shown. This modification is the same as that shown in Figs. 1 and 2 except that the position of the pin 25 is varied by a cam 30 secured to the end of a plug 31 which fits snugly in the hollow portion of the shaft instead of by a tapered plug which is screwed into and out of the hollow portion of the shaft.

Referring now to Fig. 5, which is a diagrammatic view of the wiring arrangement of a system employing my switch for controlling the speed ofan electric motor, 40 represents a motor having its field winding 41 connected in series with a resistance 42, from the opposite sides of which extend conductors 43 and 44. These conductors are respectively connected to the brushes 45 and 46 which in turn cooperate with the collector rings 4 and 5. As diagrammatically indi cated in Fig. 5, the switch is connected to the shaft of the motor armature and adapted to rotate therewith. I

The operation of the arrangement shown in Fig. 5 is as follows: When the motor is at rest, the spring 22 holds the contact 21 out of engagement with contact 16, and under these conditions the resistance 42 is connected in series with the field winding 41 of the motor. When the speed of the motor reaches a predetermined value, centrifugal force overcomes the force exerted by the spring 22 and the contact 21 moves into engagement with contact 16. Collector rings 4 and 5 are thereby connected together so that the resistance 42 is short-circuited and the field current of the motor is consequently increased to its full value. This increase in energization of the motor-field causes the speed of the motor to decrease, whereupon the contact 21 is moved out of engagement with contact 16 and consequently the electric connection between the collector rings 4 and 5 is broken. This results in the weakening of the motor field with a consequent increase in motor speed. This alternate opening and closing of the contacts 16 and 21 continues with the result that the speed of the motor is maintained substantially constant.

While I have shown several modifications and applications of my invention, I wish it retrace to be understood that I am not limited to the exact arrangements herein described and shown but seek to cover in the following claims all those modifications and embodiments which come within the spirit and scope of my invention.

What T claim as new and desire to secure by Letters Patent of the United States, is,-

1. In combination, a hollow shaft, an adjustable plug in the hollow portion of said shaft, and a centrifugally operated switch comprising a hub fastened to said shaft, two collector rings mounted on and insulated from said hub, a .contact secured to one of said rings, a centrifugally operated contact connected to the other of said rings and adapted to engage said first mentioned contact, a spring opposing the movement of said centrifugally operated contact, and means controlled by the position of said plug in said shaft for varying the opposing force of said spring.

2..Tn combination, a hollow shaft, an adjustable plug in the hollow portion of said shaft, and a centrifugally operated switch comprising a hub fastened to said shaft, two collector rings mounted on and insulated from said hub, a contact secured to one of said rings, a centrifugally operated contact connected to the other of said rings and adapted to engage said first mentioned contact, a spring opposing the movement of said centrifugally operated contact, a lever pivotally mounted on one of said collector rings, one end of said spring being fastened to said lever and the other end in engagement with said movable contact, and means controlled by the position of said plug in said shaft for varying the position of said lever to adjust the opposing force of said spring.

3. In combination, a hollow shaft, an adjustable plug in the hollow portion of said shaft, and a centrifugally operated switch comprising a hub fastened to said shaft, two collector rings mounted on and insulated from said hub, a contact secured to one of said rings,.a centrifugally operated contact connected to the other of said rings and adapted to engage said first mentioned contact, a spring opposing the movement of said centrifugally operated contact, a lever pivotally mounted on one of said collector rings, one end of said spring being fastened to said lever and the other end in engagement with said centrifugally operated contact and tending to oppose the movement thereof, and'a pin extending through a hole in said shaft and connected between one end of said lever and said plug, the other end of said lever being designed so that centrifugal force tends to hold said lever in engagement with said pin..

4. In combination, a hollow shaft, an adjustable tapered plug in the hollow portion of said shaft, and a centrifugally operated switch comprising a hub fastened to said shaft, two collector rings mounted on and insulated from said hub, a contact secured to one of said collector rings, a centrifugally operated contact connected to the other of said collector rings and adapted to engage said first mentioned contact, a lever pivotally mounted on one of said rings a spring 10 having one end fastened to said lever and the other end in engagement with said centrifugally operated contact and tending to oppose the movement of said centrifugally operated contact, and a pin extending through a hole in said shaft and connected between one end of said lever and the tapering surface of said plug.

In witness whereof I have hereunto set my hand this 26th da of January, 1920.

PXUL F. SHIVERS. 

